Rabies Guide 2010.pdf - the South African Veterinary Council

disease control if they suspect that the animal had
rabies or a positive test result is received.
The fluorescent antibody test (FAT) is the standard
diagnostic test currently used in South Africa, and
elsewhere. 164 The presence of rabies virus antigen
is demonstrated in brain smears by means of
immunofluorescence using antirabies fluorescein
conjugate. The FAT is more than 99% reliable in
experienced hands. The conjugate produced by the
Rabies Unit at ARC-OVI will also detect rabiesrelated
virus antigen. (Personal communication,
Claude Sabeta). Commercial conjugates are also
available.
Supplementary tests used include cell culture, mouse
inoculation, the polymerase chain reaction and
immunohistological tests. Histopathology, which
makes use of formalin-impregnated brain sections, is
not always informative for rabies infection but may
help to exclude conditions in the differential diagnosis
of rabies. 39
The FAT can be completed within 2 hours of receiving
suitable brain material and delays in obtaining
laboratory results are usually due to transportation
problems. 21,30 Because post-exposure prophylaxis of
humans should be instituted without delay, decisions
on the correct course of action are usually taken
before the results of veterinary diagnostic tests become
available. However, the results of laboratory tests
are used, in conjunction with the clinical history,
to decide whether antirabies prophylaxis should be
continued or discontinued.
Differential diagnosis
Rabies must be considered in the differential diagnosis
of any suspected mammalian encephalitis. Various
conditions that have been confused with rabies are
listed in Table 8. 18,40
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